Re: Reparenting processes?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> I think I have a USB serial port somewhere.  I should try that under
> 5.2 to see what happens.

When pointed at /dev/ttyU0, ctty-test prints

ctty-test: test write failed: Input/output error

but, curiously, one CRLF does get emitted to /dev/ttyU0.  It also
leaves it in a peculiar state in which the next character written to it
gets lost - or, at least, that's the best short description of what I
saw.  Specifically, I ran

# ctty-test /dev/ttyU0

and I got the EIO indication (plus "exit 1" because of the "setsid
broken for pgrp leaders" workaround) and a CRLF sent down the serial
line.  Then I ran serialconsole, a program of mine which is designed to
talk to, well, serial consoles, but which can also be used as a way to
just talk to a tty.  Using that, I then typed "xyz" at it.  The x
disappeared; the y and z showed up as normal.  Further typing appears
to work normally.

Apparently 5.2's ucom's write routine does not work right when the
device is not actually open.  Given how complex USB is, this does not
surprise me; what surprises me is that _anything_ gets through, and the
peculiar character-eating state it gets left in.

It does make me glad I did that test on a machine for which a crash or
hang would not have been more than a minor inconvenience; there clearly
are issues with at least some serial port drivers under this
circumstance.  If someone can reproduce this under 9.1, perhaps filing
a PR would be a good idea?  I'll be testing more with real hardware.

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